Anchor bolts are generally embedded in concrete for the purpose of fixation of a structural member (timber or steel) or equipment. There is another type of anchor bolt that is attached to an existing concrete floor. This type of anchor bolt used for fixation after construction is called ‘after application anchor bolt’ or ‘post-installed anchor’.
For attachment of the post-installed anchor in the existing concrete floor, a pilot hole of a predetermined depth is opened, and the post-installed anchor is inserted into and fixed to the pilot hole. There are two different types of fixation, chemical-type fixation and sleeve-type fixation. The chemical-type fixation fills the pilot hole with an adhesive and drives the anchor into the adhesive-filled pilot hole.
The sleeve-type fixation makes an insertion end of the anchor tapered to gradually increase the diameter toward an edge and inserts the anchor covered with a fixation sleeve into a pilot hole, which is formed to have a diameter substantially equal to the outer diameter of the sleeve. The sleeve-type fixation then drives the fixation sleeve in the pilot hole with a drive-in sleeve having the same diameter as that of the fixation sleeve. The driven-in fixation sleeve moves toward the edge of the anchor and is extended outward along the tapered insertion end of the anchor to bite into the inner wall of the pilot hole.
Another type of the post-installed anchor is fixed by rotation, instead of driving in the fixation sleeve. This is equivalent to formation of the tapered insertion end of the drive-in-type anchor as a nut. Rotation of the anchor moves a nut, which is temporarily tightened to the insertion end of the anchor, to enter deep inside the fixation sleeve. The fixation sleeve then rides on the tapered face of the nut to be widened or extended outward. The fixation sleeve is thus strongly pressed against and adheres to the concrete surface, so that the post-installed anchor is securely fixed to the pilot hole.